An automatic test system which calibrates and verifies the desired operation of a completed electronic instrument is commonly used in the electronic instrument field. Ordinarily, the test system is coupled to the instrument and measures the instrument against each mode of operation and each parameter in the instrument specification. In this way, the quality of each operating mode of the device is assured. In many cases, a pass/fail report may be automatically generated and include a printout indicating the values of the various parameters measured.
Electronic instruments are commercially available for performing a wide variety of operations. For example, instruments can be used to measure voltage, current, power, frequency, wave fault detection, test other instruments or devices, generate signals or waveforms. Unfortunately, it is possible that an instrument may fail to perform its intended function or it may perform each of its intended functions as designed but fail to do so accurately.
In the case of a voltage measuring instrument, the accuracy of the measurement is typically given in the product specification or data sheet. For example, a voltage meter might be required to measure a voltage in the range of 0 to 50 volts and provide a reading of that measurement within .+-.0.1 V. It is possible for a system to pass all of the automated tests except that the degree of accuracy of measurement is .+-.0.11 V rather than the specified .+-.0.1 V. Unfortunately, it is possible for a Quality Engineer, Product Engineer, or a Product Manager to arbitrarily decide to ship such a product in order to meet, for example, a production quota, keep production costs low or the like.
As manufacturing processes are dispersed to additional production facilities throughout the world, control over quality becomes even more difficult. Even if the home factory provides a satellite manufacturing facility with automatic test equipment in order to ensure the quality of the finished product, it is still possible for human intervention to ship product of substandard performance.
By allowing human intervention, it is possible that substandard instruments which perform the intended functions can be shipped to customers. While these instruments fail to meet published specifications because they perform their intended functions, many customers will be unable to detect the deficiency. Such a practice can allow inadequate instruments into the field and damage a manufacturing firm's reputation.